10GbE Network Design Question

Hello, I have a video production client that does editing off of two large SMB/AFP/NFS servers, each with multiple 10GbE ports. All editors are using Macs with Sonnet Thunderbolt 3 to 10GbE adapters or brand new Macs with built in 10GbE ports (only one in use on each currently). Currently, they have a Dell N4000 series 10GbE switch which is segregated from the internet facing network (this was to eliminate contention and also because we set the 10GbE MTU to 9000). Also, any attempt to team NICs from either server freaks the switch out.

I realize this design is far from ideal. The client will be expanding to roughly 2-3x the size, and will need additional networking equipment. I've learned a lot more about 10GbE networking since the original setup, and I don't want to recommend more Dell (we've hit random problems every few months that Dell Support has been able to fix, but always through weird fixes like disabling Green Ethernet on one port). We're partnered with Dell, which meant we got them at a steal, but everyone involved agrees they aren't the future here.

I'm looking for something that meets the following conditions:

1. Not breaking the bank. I've seen some great Ciscos that are $5-7K EACH. They will never approve them, especially if we're going to need at least 3.
2. Able to reliably switch large volumes of 10Gbps traffic at 1500 MTU or a way to route between a 9000 MTU VLAN and a 1500 MTU VLAN, with the assumption that most client endpoints will need both networks over one connection. I realize this is likely where I'm completely misunderstanding what I actually need/want to do, so any advice is appreciated.
3. Preferably with good overhauls. I'm considering also replacing the 3x 1GbE Switches (2 Netgear the client bought and a Dell) as well if the cost is feasible.

Currently, we have over 60 drops to computers. 12 go to editors workstations for 10GbE, and the others go to editors for 1 GbE and for all other employees, wifi, and phones/printers/peripherals. This will likely jump to 150+ starting in November, and being able to route all connections to one switch stack would be ideal.

We don't have firm budget numbers, but I'm aiming to come around $10K USD or so. We also will be having to expand our storage array, which is going to cost another $30K or so, and I know they'll be dropping a bunch more than that on the office expansion.